In the production of antireflection films, the provision of a layer having a specific refractive index, such as the formation of a layer having a lower refractive index than a transparent substrate film on the transparent substrate film or the formation of a layer having a higher refractive index than a transparent substrate film on the transparent substrate film followed by the formation of a layer having a lower refractive index than the transparent substrate film thereon, has hitherto been adopted in the art. Methods for controlling, that is, increasing or decreasing, the refractive index of the layer provided on the substrate film include one wherein the refractive index is varied by varying the kind of a binder resin used and one wherein ultrafine particles having a refractive index different from a binder resin are dispersed in the binder resin.
In the conventional method wherein the refractive index is varied by varying the kind of the binder resin, the control of the refractive index relies upon the selection of the resin, imposing a limitation. On the other hand, the method wherein ultrafine particles are dispersed in the binder resin to control the refractive index has an advantage that the refractive index of the resin composition can be easily controlled as desired. Since, however, homogeneous dispersion of ultrafine particles in the binder resin is so difficult that the use of such a resin composition disadvantageously results in the formation of a whitened antireflection film, making it difficult to provide an antireflection film having excellent transparency and antireflection properties.